You build it with concrete to retain the floodwaters or you construct it as a flow-through wall designed to relieve the hydrostatic pressure. Using either method, flood-proof wall construction is not a complicated engineering endeavor. The greater challenge for the environmental and civil engineers involved will be to locate and construct the wall along the Rio Grande to limit adverse environmental impacts to the local natural ecosystems that are dependent on the river for survival.
Prior to the construction of the wall, an environmental impact assessment (or statement) will need to be completed. For the Rio Grande Valley region along the Texas border, this process has been underway for many years and significant areas already possess EPA approval and permits. Nevertheless, these permits will need to be updated if design and engineering revisions are proposed.
The International Boundary and Water Commission (IWBC) is responsible for management and compliance with the boundary and water treaties of the United States and Mexico. Where differences arise, there are procedures in place to accommodate resolutions. Many projects have been executed by the US and Mexico under the applicable treaties including several current large scale flood control projects.
Finally, in regards to the premise of your article that suggests the risk of flooding is increasing due to “human-caused climate change”, this is not consistent with the findings documented in a recent University of Iowa study that evaluated USGS stream guages with NASA’s Gravity Recovery and Climate Experiment (GRACE) mission which recorded changes in “basin wetness” from 1985 through 2015. Their findings revealed that the risk of flooding is either unchanged or has decreased along our southwest border. They attribute this to the lack of rainfall and drought that has gripped the region during the period.